Method and apparatus of forming thick sheets from pulp



J. A. WIENER April 12, 1932 METHOD AND APPARATUS,OF FORMING THICK SHEETS FROM PULP Filed May 24. 1927 5 Sheets-Sheet- INVENTOR (/0347? Mwefl BY Q1 1 M4 ATTORNEYE April 12, 1932. J. A. WIENER 1,853,185

METHOD AND APPARATUS OF FORMING THICK SHEETS FROM PULP Filed May 24, 1927 3 Sheets-Sheet 2 BY 6 h Jwa/ u ATTORNEYJ April 12, 1932. w -N R I 1,853,185

METHOD AND APPARATUS OF FORMING THICK SHEETS FROM PULP Filed May 24-. 1927 a $.he ets-$heet 5 ATTORNEYS Patented Apr, 12, 1932 UNITED/sures PATENT OFFICE JOHN A. WIENER, OF LAUREL, MISSISSIPPI, ASSIGNOR TO MASONITE CORPORATION, OF

' LAUREL, MISSISSIPPI, A CORPORATION OF DELAWARE METHOD AND APPARATUS OF FORMING THICK SHEETS FROM PULIP Application filed May 24,

This invention relates to the manufac-.

the manufactureof such articles from a liquid cellulose or Wood fibre pulp, which is flowed into a sheet, dried and compressed and cut into suitable lengths.

The principal object of my invention is to provide an improvedmethod and apparatus for compressing the flowed sheet of pulp, and extracting the water therefrom.

In the embodiment of' the invention herein disclosed, the sheet is formed by flowing the liquid pulp onto the traveling screen of a Fourdrinier machine. The screen carries the sheet over a suction box and then between pressure rolls, by means 'of which much of the water is extracted from the pulp mass,

and the sheet is compressed.

In the present. invention, I operate the suction box under a partialvacuum, and the 25 pulp sheet, as it travels over the suction box, is covered by an apron of material, which travels with the sheet in'contact with its upper surface, and which is substantially impervious to passage of air, and the term .im-

pervious is used in this sense in my claims.

The effect of the suction acting on the bottom of the sheet through the screen, together with the apron which covers the top surface of the sheet, is to cause the sheet to be progressively, gradually and evenly compressed between the screen and apron. In this manner a large part of the water is squeezed out of the pulp, and the pulp. is compressed to a homogeneous sheet or board of uniform thickness.

49 The sheet is then further compressed, cut

side of the machine shown 1n Fig. 1, with the deckle wheels removed.

' into suitable lengths, and otherwise finished as desired. "7

The apron which covers the sheet as it passes over the suction box is preferably in the form of an endless belt, formed ofrubberized. fabric or similar flexible material. The apron belt is mounted above the pulp sheet, and its 'lowercourse travels with and over,.the screen, being guided so that during the first part of itsmovement' 1927. Serial in. 193,821.

over the suctionbox it is in close sealing contact with the top surface of the pulp sheet. During the latter part of its movement over the suction box, and while the pulp sheet is still tightly held down againstthe screen by the suction, the apron is guided upwardly away from the sheet. In this manner I secure the breaking away of the apron from the sheet without lifting the sheet from the traveling screen orotherwise disturbing or injuring the sheet.

There isa strong tendency to draw the screen and sheet down into the suction box.

' To prevent this, Iprovide special means for firmly supporting the screen as it travels over the mouth of the suction box. In the I form of invention herein disclosed such means consists of an endlesscarrier, located in the a suction box, immediately below the screen. The carrier extends the full width and length of the mouth of the suction box and throughout its length is in supporting contact with thebottom of the' screen. The screen and carrier movetogether, and I preferably employ a separate driving means for the carrier, so

I Cl

that the carrier, acting through its supporting contact wlth the screen, asslsts in driving the screen over the mouth of the suction box.

7 The suction box which I employ is specially constructed to withstand the atmospheric pressure to which it is subjected.

I Numerous other advantages and objects of my invention will appear from the following description taken in connection with the accompanying drawings.

Fig. I is a side elevation, partly in section and partly broken away, of a Fourdrinier machine embodying one form of my inventron. V

Flg. 2 1s a schematic top plan view of one Fig. 3 is an enlarged longitudinal sectional view of the suction box shown in Fig. 1. Fig. 4.- is a section taken on the line 4-4 of Fig. 1, and i Fig. 5 is an enlarged detail sectional view of a portion of the structure shown in Fig. 4, indicated by the arrow 5 in Fig. 4. v

The wood or otherfibrous stock used in making the pulp is disintegrated by any suitable means, preferably by exploding the stock in the manner described in United States Patent N 0. 1,578,609, granted on March 30, 1926 to lVilliam H. Mason. The mass of loose fibres formed in this manner is mixed with water to form a liquid pulp, and this is fed through a spout 0, shown at the right of Fig. 1, into an agitating tank 10 that is provided with vertical baffles or partitions 11, 12 and 13. The pulp passes through the tank 10, flowing up and down, under baffles 11 and 13 and over baflie 12, and is delivered from the tank 10, through an opening 16, into a trough 18. Between the bottoms of the baffles 11 and 13 and the bottom of the tank 10 are rotating hollow perforated cylinders 17, which act in a manner well known in the art to agitate the pulp, and make it of uniform consistency.

Trough 18has a flat bottom 19, and side plates 20, preferably formed of thin brass. The bottom of trough 18 terminates at a point indicated by 22 in Fig. l, and at this point the pulp passes to a traveling endless screen 26, which carries the pulp over the table rolls 27, thence carries the pulp in the form of a sheet 28 over the mouth of the suction box 30, over the table rolls 32, and under the screen tightening roll 83, and finally between the upper and lower rolls of pairs of press rolls indicated at 35.

From this point the pulp sheet 28, which has been considerably pressed and freed from water, passes on to a cutting machine, not shown, and the carrier screen 26 passes down around the last of the lower press rolls 35, and thence back to the breast roll 37.

Press rolls and breast rolls 37 are both driven from a suitable source of power, not shown, and these rolls form part of the driving means for the carrier screen 26. Adj ustable idle rollers 38, serve to maintain the carrier screen 26 under proper tension.

The sides 20 of the trough 18 extend beyond the point 22, at which the bottom of the trough terminates, to a point 40 (Fig. 1) approximately midway of the length of suction box 30, and the carrier screen 26 extends laterally under the extended side plates 20, which thus form a means for preventing the pulp from flowing off the edges of the screen. Beyond the forward ends of the side plates 20 the pulp is retained on the screen by deckle straps 42, which move with the screen 26, resting on the margins of the screen 26, as indicated in Fig. 5, which shows the margins of the screen 26 resting on the top of the side wall of the suction box, and a deckle strap 42 supported on the margin of the screen.

The deckle straps 42, which are endless rubber belts, pass around wheels 44 and 45, and as shown in Fig. 2, these deckle straps are located outside plates 20 of the trough 18. The deckle straps assist plates 20 in preventing the pulp from flowing off the ed es of the screen, and beyond plates 20 the dec 1c straps support the pulp sheet at each of its edges, and form an air seal in conjunction with apron 46, which is received between the deckle straps.

Moving into contact with the upper surface of the pulp sheet as it moves over the mouth of the suction box, is an endless apron 46, formed of impervious, or in other words air-tight, material, such as rubberized fabric, which preferably has a smooth outer surface. The apron 46 passes over upper rolls 48 and 49 (one or both of which may be a tightener roll), thence down around roll 50, at which point it moves into contact with the pulp. It then travels with the pulp to roll 51, which is located somewhat below roll 50, so as to guide the apron 46 in such a way that it will remain in contact with the pulp sheet as the sheet becomes progressively thinner under'the suction from the suction box 30.

From roll 51 apron 46 passes upward at a slight incline away from the screen 26 and pulp sheet 28. Beyond the roll 51 the apron leaves the upper surface of the pulp sheet 28, and passes under and around roll 52. The pulp sheet is at this time still tightly held by the suction against the carrier screen 26, and the breaking away of the apron from the pulp sheet is effected without raising or disturbing the sheet.

From roll 52 the apron 46 passes back to upper roll 48. One or both of rolls 48, 49 may be adjustable to regulate the tension of the apron 46.

I may, if desired, provide separate driving means for the apron 46. I find, however, that the apron may be satisfactorily driven from the moving pulp sheet through the frictional, sealing surface engagement between the apron and sheet, the apron being held forcibly down on the moving sheet by the partial vacuum in suction box 30.

The suction box 30, which is built to withstand a high vacuum, has sides formed of L-shaped metal members 60, shown in section in Figs. 4 and 5. Said side members are preferably formed with broad upper flanges 60 to form trackways for the outer edges of screen 26 and the deckle straps 42. The ends of the box 30 are semi-cylin drical and are welded to the sides 60 and to the bottom 62. The bottom 62 is formed of metal plates which are reinforced by iongitudinal T-bars 63. The metal plates are welded to the sides and the ends of the box and incline don-nwardly, as shown in Figs. 1 and 3, to a sump or trough 64, formed of a pipe 65, part of which has been cut away, and the cut edges welded to the bottom plates and sides.

The remainder or uncut portions of the pipe 65 extend outwardly at opposite sides of the suction box 30 and form passages communicating with a suction pump not shown. By employing suction passages at opposite sides of the suction box, an equal amount of suction is created at both sidesof the center of the pulp sheet. One or more handholes' 30', suitably closed with hand-hole plates, may be provided 'to give access to the interior of suction box 30 when desired.

In practice, I operate the suction box under a vacuum-of, for example, three inches or more mercury. As the mouth of the suction box in certain machines is approximately four feet wide and nine feet long, the suction creates an enormous downward pressure on the screen and pulp sheet, tending to draw them into the suction box. To prevent this, I provide ameans for supporting the screen and pulp sheet as they pass over the suction box.

Such supporting means comprises an endless carrier or conveyor which is very stiff and strong in its crosswise direction and .at the same time flexible in the longitudinal direction, so that it is adapted to run on sprocket wheels or the like. In the present form of my invention this means comprises an endless, carrier 67, mounted in the suctionbox. This carrier comprises two series of sprocket wheels 68, mounted on parallel transverse shafts 70 and 71, journaled in the sides of the suction box 30. The carrier is driven at the same rate as the Fourdrinier shaped brackets 78, which are secured to opposite sides of each link. The bars 76 are formed with cylindrical outer surfaces, and the top bars of the carrier move with the screen 26 and bear against the bottom of the screen, thereby supporting the screen as it moves over the mouth of the suction box. As the carrier 67 is separately driven, the carrier, through its supporting contact with the screen,.may act as a driving means for the screen The upper course of the carrier, as it travels with the screen,is supported by'longitudinally extending metal T-shaped members 80, which in turn are supported by a series "of transverse bars or beams 81, carried at their ends by members 82 secured'to the sides of the suction box. The T-shaped members 80 extend upwardly into contact with the bottoms "(if the carrier chains the links of the.., chains" 75 being provided with rollers 7 5a, running on the topsofthe members as the chain moves. 1

' v I claim the sheet 28 is carried on screen 26 and under I the screen belt 83, which runs under the upper set of press rolls 35 and over idler roll 84 and the adjustable tightener roll 33. Roll 33 can also be raised and lowered by the adjusting screw 85.so as to bring screen belt 83 into engagement with the pulp sheet gradually in the course of the reach of said screen belt 83 between tightener roll 33 and the first roll of press rolls 35. The pressure of rolls 35 can be controlled by the adjustment of weights 86 along lever arms 87 the arms 87 being connected with the upper press rolls through rods '88 and removable roll mountings 89.

1. The method of forming a homogeneous pressed sheet from liquid pulp supported on a flat wire screen, which comprises covering the top of the pulp with an impervious apron,

' supported to permit its vertical movement,

pressed sheet from liquid flbre pulp, which comprises flowing the pulp onto a fiat wire screen, covering the top of the flowed pulp with an impervious apron supported so'as ,to

permit its vertical movement, and exhausting the air from beneath said screen,'whereby the pulp is tightly squeezed between the apron and screen and water is forced out of said pulp. y

3. The method of forming a homogeneous pressed sheet from liquid pulp, which comprises flowing the pulp onto a flat wire screen,

covering the top of the flowed pulp with an apron of impervious flexible material, exhausting air under partial vacuum from beneath said screen, whereby, due to the suction created, the pulp is tightly squeezed between the screen and apron, and removing said apron from said pulp sheet, progres- 'sively along said sheet, while the sheet is still held against the screen by the suction.

4:. The method of forming a homogeneous pressed sheet from liquid pulp, which comprises flowing the pulp onto a flat wire' screen, covering the top of the flowed pulp with an apron of impervious flexible material, having a smooth lower surface, exhausting air under partial vacuum from beneath said screen, whereby, due to the suction created, the pulp is tightly squeezed between said screen and apron, and removing said,

apron from the pulp sheet, progressively along said sheet, while the sheet is still held against the screen by said suction.

5. An apparatus for forming a pressed sheet from wet pulp, comprising a traveling carrier screen, means for feeding soft wet pulp-onto said screen, an impervious apron movable onto said pulp on said screen, and movable with said pulp and screen, a suction box located beneath said screen and apron, and means for exhausting air from said suction box, whereby said pulp is compressed between said apron and screen.

6. An apparatus for forming a sheet from wet fibrous pulp, comprising an endless carrier screen, means for feeding soft wet pulp onto said screen, a suction box located beneath said screen, and an endless apron of impervious material, movable downwardly into contact with the upper surface of said pulp, and thence with said pulp as it is moved by said screen above the mouth of said suction box, and means for exhausting'air from said suction box, whereby said pulp is compressed between said apron and screen.

7. An apparatus for forming a pressed sheet from wet pulp, comprising a screen upon which said pulp is supported, an impervious apron supported in contact with the upper surface ofsaid pulp, and means for exhausting air from beneath said screen, whereby the pulp is compressed between said apron and screen.

8. An apparatus for forming a sheet from wet fibrous pulp, comprising an endless carrier screen, means for feeding-soft wet pulp onto said screen, a suction box located beneath said screen, and an endless apron of impervious material, movable downwardly into contact with the upper surface of said pulp, and thence with said pulp as it is moved by said screen above the mouth of said suction box, and means for exhausting air from said suction box, whereby said pulp is compressed between said apron and screen, said apron, as it moves with said pulp, being guidedtowards said screen so that it remains into contact with said pulp as the sheet of pulp becomes progressively thinner under said compression.

9. An apparatus for forming a sheet from wet pulp, comprising an end-less carrier screen,

means for feeding soft wet pulp onto saidsaid pulp, and means for exhausting air from said suction box, whereby during the initial movement of the pulp over the suction box the pulp is com ressed between said apron and screen, and t e apron is then withdrawn from the pulp while the pulp is held on the screen by the suction from said suction box.

10. An apparatus for forming a sheet from wet pulp, comprising an endless carrier screen, means for feeding soft wet pulp onto saidscreen, a suction box located beneath said screen, an endless apron of impervious material movable downwardly into contact with the upper surface of said pulp, and thence with said pulp as it moves above the mouth of said suction box, whereby said pulp is compressed between said apron and screen, and means on the edges of the pulp sheet for retaining the pulp on the screen, said apron and said last-named means co-operating to form a seal to prevent access of air to said suction box.

11. An apparatus for forming a sheet from wet pulp, comprising an endless carrier screen, means for feeding soft wet pulp onto said screen,' a suction box located beneath said screen, an endless apron of impervious material movable downwardly into contact with the upper surface of said pulp, and thence with said pulp as it is moved by said screen above the mouth of said suction box, means for exhausting air from said suction box whereby said pulp is compressed between said apron and screen, and deckle straps supported on said screen at its margins, and movable with said screen, said decltle straps serving to retain said pulp on said screen, and cooperating with said apron to prevent access of air to said suction box.

12. The combination with an endless form ing screen of a Fourdrinier machine, means at one end thereof for flowing fibre thereon in a thick sheet and a suction box cooperating with said screen at an intermediate point thereof for withdrawing water therefrom, of a plurality of pairs of oppositely disposed press rolls receiving said screen therebetween beyond the suction box and through which the sheet is passed while still supported by said endless forming screen, and a second endles screen interposed between the top of the sheet and the top pressure rolls.

13. The method of forming a homogeneous sheet of low water content from liquid pulp,

which consists of carrying the liquid pulp on a traveling support pervious-to-air-and-water, covering the liquid pulp with a traveling, impervious-to-air apron, and exhausting air from beneath said support whereby water is withdrawn from the pulp.

14. The combination with an endless forming screen of a Fourdrinier machine, means at one end thereof for flowing fibre thereon in a thick sheet and a suction box cooperating with said screen at an intermediate point thereof for withdrawing water therefrom, of a pair of oppositely disposed press rolls receiving said screen therebetween beyond the suction box and through which the sheet is passed and by which the same is positively pressed while still supported by said endless forming screen, and a second endless screen interposed between the top of the sheet and the top pressure roll.

15. The combination with an endlessforming screen of a Fourdrinier machine, means at one end thereof for flowing fiber thereon in a thick sheet, of a pair of oppositely disposed pressure rolls receiving said screen therebetween and through which the sheet is passed while still supported by said endless forming screen, the top pressure roll being weighted and freely movable towards the lower roll to exert a pressure upon saidsheet,

l5 and an endless belt interposed between the top of the sheet and the top pressure roll.

16. The combination with the endless forming screen of a Fourdrinier machine and means for forming a thick pulp sheet thereon, of a pair of pressure rolls, the .lower roll of said pair being encircled by said forming screen, and an endless belt encircling the upper roll of said pair, the sheet being interposed between said forming screen and said belt while passing between said pressure rolls.

17. The combination with the endless forming screen of a Fourdrinier machine and means for forming a thick pulp sheet thereon, of a pairof pressure rolls, the lower roll of said pair being encircled by said forming screen and an endless belt moving toward said forming screen with a gradual approach and encircling the upper roll of saidpair, the sheet being interposed between said forming screen and said belt while passing between said pressure rolls.

18. The combination with the endless forming screen of a Fourdrinier machine and means for forming a thick pulp sheet thereon, of a pair of pressure rolls, the lower roll of said pair being encircled by said forming screen, and an endless belt encircling the upper roll of said pair, the sheet being interposed between said forming screen and said belt while passing between said pressure rolls. andmeans for varying the angle at which said belt approaches the forming screen. I

19. The combination with the endless forming screen of a Fourdrinier machine and means for forming a thick pulp sheet thereof, of a pair of pressure rolls, the lower roll of said pair being encircled by said forming screen, and a second endless screen encircling 55, the upper roll of said pair, the sheet being interposed between said forming screen and said second screen while passing between said pressure rolls.

' In testimony whereof, I have signed my name hereto.

JOHN A. WIENER. 

